JP2014104432A - Sludge treatment apparatus and method of manufacturing phosphorus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a sanitary sludge treatment apparatus capable of providing solid phosphorus which is dried in a short time.SOLUTION: There is provided a sludge treatment apparatus for treating sludge, recovering phosphorus and discharging effluent, having a phosphorus recovering part for recovering solid phosphorus by application of a crystallization method and a washing part of washing the solid phosphorus by an alkali solution.

Description

  The present invention relates to a sludge treatment apparatus and a method for producing phosphorus.

Conventionally, a method and a recovery device for recovering phosphorus from human waste or septic tank sludge have been proposed.
For example, Patent Document 1 discloses an organic wastewater or sludge treatment system incorporating an anaerobic treatment step, and a magnesium ammonium phosphate separation step for taking out magnesium ammonium phosphate generated in sludge in the anaerobic digestion step from the system. A process for reducing sludge with respect to magnesium ammonium phosphate desorbed sludge after removing magnesium ammonium phosphate particles dispersed in the sludge in the magnesium ammonium phosphate separation process, the magnesium ammonium phosphate separation Magnesium ammonium phosphate-magnesium phosphate contact step of mixing or contacting a solution containing magnesium ions with the magnesium ammonium phosphate concentrated suspension separated in the step, the magnesium ammonium phosphate-magnesium A step of recovering the magnesium ammonium phosphate particles from the liquid containing the magnesium ammonium phosphate concentrated suspension after the liquid contact step, and the removal of the collected solid magnesium ammonium phosphate particles; A method for treating organic wastewater and sludge characterized by having a step of returning the suspension after separation to the anaerobic digestion step or the previous step is described.

  In Patent Document 2, in a system for supplying a user with MAP recovered from a water treatment or sludge treatment plant capable of recovering phosphorus as MAP (magnesium ammonium phosphate), from the plant location to the MAP user, In order to efficiently supply the required amount of MAP at the required time, the scale of the MAP recovery device of the plant is specified, the operation time of the MAP recovery device is controlled, and the constantly changing amount and purity of MAP are determined. There is described a MAP collection / distribution system characterized by comprising a control means that can control the MAP recovery amount and the MAP purity by adjusting the appropriate amount and the appropriate purity.

Japanese Patent No. 3664398 Japanese Patent No. 4262068

When recovering phosphorus from sludge such as human waste or septic tank sludge, it is important that the recovered phosphorus is hygienic so that it can be reused as fertilizer.
Moreover, it is preferable that phosphorus is dried quickly after being recovered. If the time until drying is short, for example, the time of carrying out of the system can be freely selected, which is preferable in terms of operation. The recovered phosphorus is usually left in the system (in the factory premises, etc.) and dried. However, if the time until drying is long, the residence time in the system becomes long. It is not preferable because a large site must be secured.

  However, the conventional phosphorus recovery method and phosphorus recovery apparatus have room for improvement in terms of recovering hygienic phosphorus. Further, the recovered phosphorus is inconvenient because it takes a long time to dry.

The present invention aims to solve the above-described problems.
That is, an object of the present invention is to provide a sludge treatment apparatus and a method for producing phosphorus that are hygienic and obtain solid phosphorus that dries in a short time.

The inventor has intensively studied to solve the above-mentioned problems, and has completed the present invention.
The present invention includes the following (1) to (6).
(1) A sludge treatment device for treating sludge to recover phosphorus and discharging discharged water,
Applying a crystallization method, a phosphorus recovery unit that recovers solid phosphorus, which is solid phosphorus,
A washing section for washing the solid phosphorus with an alkaline solution;
A sludge treatment apparatus.
(2) Furthermore, it has a deodorization part which collects the odor component generated from the sludge, deodorizes it, and discharges alkaline waste liquid;
The sludge treatment apparatus according to (1), wherein the cleaning unit uses the alkaline waste liquid as the alkaline solution.
(3) Furthermore, it has a sterilization section for discharging the discharged water adjusted to be alkaline,
The sludge treatment apparatus according to (1) or (2), wherein the discharged water is used as the alkaline solution in the cleaning unit.
(4) A method for producing phosphorus in which sludge is treated to recover phosphorus and discharge effluent water,
A phosphorus recovery step of recovering solid phosphorus, which is solid phosphorus, by applying a crystallization method;
A washing step of washing the solid phosphorus with an alkaline solution;
The manufacturing method of phosphorus which has this.
(5) Furthermore, it has a deodorizing step of recovering odor components generated from the sludge, performing a deodorizing process, and discharging an alkaline waste liquid,
In the said washing | cleaning process, the manufacturing method of phosphorus as described in said (4) using the said alkaline waste liquid as the said alkaline solution.
(6) Furthermore, it has the sterilization process which discharges the discharge water adjusted to alkalinity,
The method for producing phosphorus according to (4) or (5) above, wherein in the washing step, the discharged water is used as the alkaline solution.

  ADVANTAGE OF THE INVENTION According to this invention, the sludge processing apparatus which can obtain the solid phosphorus which is hygienic and can be dried in a short time, and the manufacturing method of phosphorus can be provided.

1 is a schematic view of a preferred embodiment of the apparatus of the present invention. It is the schematic of the apparatus used in the Example.

The present invention will be described.
The present invention is a sludge treatment apparatus for treating sludge to collect phosphorus and discharging discharged water, and applying a crystallization method to collect solid phosphorus, which is solid phosphorus, A sludge treatment apparatus having a washing unit for washing the solid phosphorus with an alkaline solution.
Hereinafter, such a sludge treatment apparatus is also referred to as “the apparatus of the present invention”.

The present invention also relates to a method for producing phosphorus in which sludge is treated to recover phosphorus, and discharged water is discharged, wherein the phosphorus is recovered by applying a crystallization method to recover solid phosphorus, which is solid phosphorus. It is the manufacturing method of phosphorus which has a collection | recovery process and the washing | cleaning process which wash | cleans the said solid phosphorus with an alkaline solution.
Hereinafter, such a method for producing phosphorus is also referred to as “the production method of the present invention”.

  The production method of the present invention can be performed using the apparatus of the present invention.

  In the following, the simple description of “the present invention” means both “the apparatus of the present invention” and “the production method of the present invention”.

  The sludge to be treated in the present invention is not particularly limited as long as it is sludge containing phosphorus (at least part of which is preferably phosphorous phosphorus). Examples of the sludge include human waste and septic tank sludge. That is, in the present invention, “sludge” includes “human waste”. The sludge may be one after removing the residue contained in human waste or septic tank sludge.

  The sludge is preferably human waste (including live urine). That is, in the present invention, human waste can be preferably treated.

The components of sludge are, for example, pH = 6-9, SS = 3,000-15,000 mg / L, phosphorus content (total phosphorus) = 25-800 mg / L, phosphate phosphorus concentration = 20-300 mg / L Ammonia nitrogen concentration = 500 to 5,000 mg / L.
Among the sludge, the components of human waste are, for example, pH 7.0 to 8.0, SS = 5,000 to 15,000 mg / L, phosphorus content (total phosphorus) = 25 to 800 mg / L (preferably 100 -200 mg / L), phosphorous phosphorus concentration = 20-200 mg / L (preferably 10-40 mg / L), and ammoniacal nitrogen concentration = 500-5,000 mg / L.

<Phosphorus recovery unit, phosphorus recovery process>
The phosphorus collection | recovery part in the apparatus of this invention is demonstrated.
In the apparatus of the present invention, solid phosphorus, which is solid phosphorus, is recovered by applying a crystallization method.
The object to which the crystallization method is applied may be the sludge, or may be obtained after processing the sludge. After adding the polymer flocculant to the sludge, at least a part is subjected to solid-liquid separation, and a crystallization method is applied to the separation liquid which is mainly a liquid part to recover solid phosphorus which is solid phosphorus. preferable.

Here, the crystallization method is a method based on a reaction of crystallizing phosphorus in the liquid on the seed crystal surface, and mainly includes a MAP method and a HAP method.
The MAP method is a method that utilizes the crystallization phenomenon of MAP generated by the reaction of PO ₄ ³⁻ , NH ₄ ⁺ , and Mg ^{2+ in} the liquid, and an Mg ion source (magnesium chloride) is added to sludge containing phosphorus and ammonium ions. , Magnesium hydroxide, etc.) is added and brought into contact with the seed crystal in a supersaturated state to cause MAP to crystallize on the surface of the seed crystal and collect it.
HAP method, PO ₄ ^3- in the liquid, Ca ^2+, OH ^- reactions (. Which hereinafter referred to as HAP) hydroxyapatite produced by the a method using the crystallization phenomenon, Ca ² sludge containing phosphorus By adding ⁺ and OH ⁻ and contacting with the seed crystal in a supersaturated state, HAP is crystallized on the surface of the seed crystal and recovered.

  As the phosphorus recovery unit, a conventionally known crystallization reaction tank can be used, but a fluid type capable of high-speed processing can be preferably used.

The crystallization reaction is preferably performed at a pH of about 7.5 to 10.0, and more preferably about 8.0 to 9.5. It is preferable to add a pH adjuster to the reaction bath (crystallization reactor) so as to achieve such a pH. Examples of the pH adjuster include alkalis such as NaOH and acids such as sulfuric acid.
In addition, in the case of the MAP method, the Mg ion source may be added so that the Mg ion concentration in the reaction bath is about 1.2 to 1.5 times in molar ratio with respect to the phosphate phosphorus concentration. preferable.
Moreover, you may add an ammonium ion source as needed.
In the case of the HAP method, the Ca ion source may be added so that the Ca ion concentration in the reaction bath is about 1.2 to 1.5 times in molar ratio to the phosphate phosphorus concentration. preferable.
About other conditions, it can carry out within the conventionally well-known condition range at the time of performing a crystallization method.

  By such a phosphorus collection | recovery part, the phosphorus collection | recovery process in the manufacturing method of this invention can be performed.

An unsanitary substance derived from the sludge may adhere to at least the surface of solid phosphorus, which is solid phosphorus obtained by the phosphorus recovery part or the phosphorus recovery process. In this case, an odor may be emitted. When using solid phosphorus as a fertilizer etc., it is more hygienic and it is preferable not to emit an odor.
Moreover, immediately after collection | recovery (for example, immediately after extracting from a crystallization reaction tank), a moisture content is very high. Therefore, after drying this in the system, it is necessary to carry it out of the system, but the time until drying (the water content is about 2% by mass) is usually about one month or more. . It is preferable if this time can be shortened.

<Washing part, washing process>
The cleaning unit in the apparatus of the present invention will be described.
In the apparatus of the present invention, the solid phosphorus recovered as described above is washed with an alkaline solution.

Here, the alkaline solution means an alkaline liquid.
In the present invention, the alkaline solution preferably has a pH of 8.0 to 11.0, and more preferably 9.0 to 10.0.
The alkaline solution preferably contains sodium hydroxide. In this case, the concentration of sodium hydroxide is preferably 500 to 3000 mg / L, and more preferably 1000 to 2500 mg / L.
The alkaline solution preferably contains sodium hypochlorite. In this case, the concentration of hypochlorous acid is preferably 100 to 1000 mg / L, and more preferably 300 to 500 mg / L.
The alkaline solution is preferably an alkaline aqueous solution.

  As will be described later, it is preferable to use an alkaline waste liquid generated in the system as the alkaline solution.

  The method for washing solid phosphorus with an alkaline solution is not particularly limited, and for example, it can be washed by a conventionally known method. For example, it can be washed by immersing solid phosphorus in an alkaline solution and stirring.

  As the cleaning unit, equipment capable of receiving the solid phosphorus and the alkaline solution and cleaning the solid phosphorus can be used. For example, a reaction vessel equipped with a conventionally known stirrer can be used.

  In addition, for example, when the reaction vessel is used as described above and the solid phosphorus and the alkali solution are put and washed therein, the pH and alkali concentration of the alkali solution in the reaction vessel may gradually change. Therefore, it is preferable to adjust the pH and concentration of the alkaline solution to appropriate values by adding a new alkaline solution to the reaction vessel during washing. Here, when adding a new alkaline solution to a reaction vessel or the like, it is necessary to discharge the alkaline solution that has already been used for washing from the reaction vessel or the like. And preferably used as a pH adjuster.

  By such a cleaning part, the cleaning process in the manufacturing method of the present invention can be performed.

  The present inventor has found that according to such a washing section or washing step, solid phosphorus that is hygienic and can be dried in a short time can be obtained. Specifically, according to the present invention, it is almost free of E. coli, and more specifically, after a few hours (generally 12 to 24) if left in a room or outdoors (room temperature and normal pressure) for a short time. Within a period of time, solid phosphorus that is easy to dry can be obtained so that the water content is about 2% by mass. Since it is hygienic to such an extent that it hardly contains Escherichia coli, phosphorus obtained by the present invention can be preferably used as a fertilizer or the like. Moreover, since it dries in several hours, since it can choose freely, for example, the time of carrying out out of a system, it is preferable on operation.

In addition, it is preferable to blow the solid phosphorus collected by the washing section or the washing process using a blower or the like because the drying is performed in a shorter time.
Thus, it is preferable that the apparatus of this invention is provided with the drying part which dries the solid phosphorus collect | recovered by the washing | cleaning part.
Moreover, it is preferable that the manufacturing method of this invention is equipped with the drying process which dries the solid phosphorus collect | recovered by the washing | cleaning process in this way.

Next, the suitable aspect of the apparatus of this invention is demonstrated using FIG.
A preferred embodiment (apparatus 10) of the apparatus of the present invention shown in FIG. 1 includes a receiving part 12, a polymer flocculant addition means 14, a concentration part 16, a phosphorus recovery part 18, an inorganic flocculant addition means 20, The dehydrating unit 22, the mixing unit 24, the biological treatment unit 26, the sterilizing unit 28, the deodorizing unit 30, and the cleaning unit 32 are included.

<Reception Department>
In the apparatus 10, the receiving unit 12 serves to receive the sludge 40 and send it to the concentrating unit 16 with a desired supply amount.
When the apparatus of this invention has a receiving part, a receiving part should just play such a role, For example, a conventionally well-known receiving tank (tank etc.) can be used.

<Polymer flocculant addition means, polymer flocculant addition step>
In the apparatus 10, the polymer flocculant adding means 14 has a function of adding the polymer flocculant to the sludge 40.
When the apparatus of the present invention has a polymer flocculant addition means, the polymer flocculant addition means is not particularly limited as long as it can add a desired amount of the polymer flocculant to sludge. For example, a powdery or liquid polymer flocculant is added to water to obtain an aqueous solution in which the concentration of the polymer flocculant is 0.1 to 0.3% by mass (preferably about 0.2% by mass). Thereafter, means for adding using a chemical injection pump (for example, a diaphragm pump or a Mono pump) can be mentioned.

  The polymer flocculant addition means is preferably an embodiment in which, for example, a flocculant tank equipped with a stirring device is installed between the receiving part and the concentration part, and the polymer flocculant can be added thereto. Moreover, the aspect which can add a polymer flocculent into a receiving part may be sufficient as a polymer flocculent addition means. Furthermore, if a device capable of stirring the inside of the coagulation tank or the receiving part is installed, the polymer coagulant added by the polymer coagulant adding means can be stirred by using the apparatus. This is preferable because the reaction rate can be increased.

The polymer flocculant plays a role of aggregating SS (floating matter) in sludge and facilitating solid-liquid separation. As a result, most of the phosphorous phosphorus contained in the sludge is contained in the separation liquid discharged from the concentration section.
The polymer flocculant should just be what plays such a role. For example, a cationic polymer flocculant, an amphoteric polymer flocculant and the like can be mentioned, and the optimum type is selected depending on the properties of the sludge.

  The addition amount of the polymer flocculant varies depending on the properties of the sludge, and also varies depending on the type of the polymer flocculant used, but is 1.0 to 3.0 with respect to the solid dry amount (DS) in the sludge. It is preferable that it is mass%, and it is more preferable that it is 2.0-2.5 mass%.

  The production method of the present invention preferably includes a polymer flocculant addition step that can be performed by such a polymer flocculant addition means.

<Concentration part, concentration process>
In the apparatus 10, the concentrating unit 16 performs solid-liquid separation on at least a part of the sludge 40 after the addition of the polymer flocculant, and the agglomerated sludge 42 which is a part where SS contained in the sludge 40 is agglomerated and mainly a liquid part. A certain separation liquid 44 is discharged.
As the concentration unit, for example, a wedge wire screen or a rotary screen can be used. Here, these openings are preferably 0.5 to 1.0 mm.

  The production method of the present invention preferably includes a concentration step that can be performed by such a concentration unit.

<Phosphorus recovery unit, phosphorus recovery process>
In the apparatus 10, the phosphorus recovery unit 18 applies a crystallization method to the separation liquid 44 to recover solid phosphorus 46 that is solid phosphorus, and discharges the remaining dephosphorization liquid 48.

  The phosphorus recovery unit is as described above.

<Inorganic flocculant addition means, inorganic flocculant addition step>
In the apparatus 10, the inorganic flocculant adding means 20 has a function of adding an inorganic flocculant to the flocculated sludge 42.

When the apparatus of the present invention has an inorganic flocculant addition means, the inorganic flocculant addition means is not particularly limited as long as the inorganic flocculant addition means can add a desired amount of the inorganic flocculant to the aggregated sludge.
Moreover, it is preferable that the inorganic flocculant addition means is an aspect in which, for example, an aggregating tank is installed between the concentration unit and the dehydration unit, and the inorganic flocculant can be added thereto. Further, if a device capable of stirring the inside of the coagulation tank is further installed, the reaction rate of the inorganic coagulant added by the inorganic coagulant adding means can be increased by stirring the inside of the coagulation tank using this device. Therefore, it is preferable.

  Inorganic flocculants are those that agglomerate SS as in the case of polymer flocculants, but by adding to the aggregated sludge that has been agglomerated by the polymer flocculants, the flocs are further strengthened and easy to dehydrate. It plays the role of changing. This facilitates the separation of moisture and other components in the coagulated sludge in the next dewatering unit 22.

  The inorganic flocculant should just be what plays such a role. Examples thereof include ferric chloride, aluminum sulfate, aluminum chloride, polyaluminum chloride, ferric sulfate, polyiron sulfate, polyferric sulfate, and polyferric chloride. Of these, ferric sulfate is preferable.

  The amount of the inorganic flocculant added varies depending on the properties of the flocculent sludge, etc., and also varies depending on the type of inorganic flocculant used, but is 2.0 to 7.0 with respect to the solid matter dry amount (DS) in the flocculent sludge. The mass is preferable, and about 5% by mass is more preferable.

  The production method of the present invention preferably includes an inorganic flocculant addition step that can be performed by such an inorganic flocculant addition means.

<Dehydration part, dehydration process>
In the apparatus 10, the dewatering unit 22 dehydrates the coagulated sludge 42 after the inorganic coagulant is added, and discharges the dewatered sludge 50 and the dehydrated drainage liquid 52.

  When the apparatus of the present invention has a dewatering part, the dewatering part may be an apparatus that can discharge dewatered wastewater and dehydrated sludge having a low water content by dewatering the coagulated sludge. A machine can be used. For example, a belt press dehydrator, a screw press dehydrator, or a centrifugal dehydrator can be used.

  The production method of the present invention preferably includes a dehydration step that can be performed by such a dehydration unit.

<Mixing section, mixing process>
In the apparatus 10, the mixing unit 24 receives the dephosphorization liquid 48 and the dehydrated drainage liquid 52 and discharges the mixed drainage liquid 54 obtained by mixing them.

  When the apparatus of this invention has a mixing part, the mixing part should just accept a dephosphorization liquid and a dehydration drainage liquid, and can mix these, for example, a conventionally well-known reaction tank can be used. Moreover, it is preferable that the mixing part is equipped with a stirrer so that the dephosphorization liquid and the dehydrated waste liquid are further mixed.

  The production method of the present invention preferably includes a mixing step that can be performed by such a mixing unit.

<Biological treatment department, biological treatment process>
In the apparatus 10, the biological treatment unit 26 treats the mixed waste liquid 54 by the activated sludge method. Among the activated sludge methods, the biological nitrification denitrification method is preferable.
The biological treatment unit 26 applies a conventionally known activated sludge method to the mixed waste liquid 54, and further performs secondary denitrification treatment, aeration treatment, precipitation treatment, and the like as necessary. If it is a thing of the aspect which can obtain the waste liquid (biological treatment waste liquid 55) which can be discharged to a river etc. by processing, it will not specifically limit, For example, a conventionally well-known installation can be used. Specifically, there is a facility that includes a denitrification tank and a nitrification tank and can treat the mixed waste liquid 54 with activated sludge.

  The production method of the present invention preferably includes a biological treatment process that can be performed by such a biological treatment unit.

<Sterilization part, sterilization process>
In the apparatus 10, the sterilizing unit 28 adjusts the biological treatment drainage 55 discharged from the biological processing unit 26 to be alkaline and discharges it as discharged water 56.
The sterilizing unit 28 kills microorganisms (such as Escherichia coli) contained in the biological treatment drainage 55, which is the drainage discharged from the biological processing unit 28, so that it can be discharged into a river or the like. By adjusting to alkalinity, microorganisms are killed.

  In order to make it alkaline, a chemical is added to the waste liquid treated in the biological treatment unit 26. Conventionally known chemicals can be used. For example, sodium hydroxide can be used.

  A chemical is added so that the pH of the discharged water 56 is preferably 5.8 to 8.6, more preferably 7.0 to 8.0, and discharged (discharged) to a river or the like.

The device of the present invention preferably has a sterilization section.
It is preferable that the manufacturing method of this invention is equipped with the sterilization process which can be performed by such a sterilization part.

<Deodorization part, deodorization process>
In the apparatus 10, the deodorization unit 30 collects odor components generated from the sludge 40 and discharges the alkaline waste liquid 58.
In the apparatus 10, a ventilator equipped with a blower, an exhaust fan, or the like is installed on the upper part of each part (each tank) or on a belt conveyor so that the odor component derived from the sludge 40 is difficult to diffuse into the atmosphere. . Then, the odor components (H ₂ S, methyl mercaptan, etc.) collected thereby are processed by the deodorization unit 30. The deodorization unit 30 oxidizes H ₂ S contained in the odor component into sulfuric acid (H ₂ SO ₄ ) by the action of living organisms, or acid (hydrochloric acid or sulfuric acid) or alkali (sodium hydroxide or sodium hypochlorite). Use to neutralize and deodorize. The deodorization part 30 can utilize the conventionally well-known apparatus which can perform such a deodorizing process.
And from the deodorizing part 30, acidic acid waste liquid and alkaline alkaline waste liquid 58 are discharged | emitted. In the present invention, it is desirable to use an alkaline waste liquid.

  The pH of the alkaline waste liquid 58 is generally 8.0 to 12.0, but preferably 9.0 to 10.0.

The apparatus of the present invention preferably has a deodorizing part.
It is preferable that the manufacturing method of this invention is equipped with the deodorizing process which can be performed by such a deodorizing part.

<Washing part, washing process>
In the cleaning unit 32 of the apparatus 10, the solid phosphorus 46 is cleaned with the alkaline waste liquid 58 and / or the discharged water 56.

  The cleaning unit is as described above.

  Next, the process flow when the sludge 40 is processed by the apparatus 10 which is a preferred embodiment of the apparatus of the present invention as described above will be described.

  First, the sludge 40 is received by the receiving unit 12. And the sludge 40 is sent toward the concentration part 16 by the desired supply amount. Here, after being discharged from the receiving unit 12 and before being supplied to the concentrating unit 16, the polymer flocculant is added to the sludge 40 by the polymer flocculant adding means 14 (polymer flocculant adding step). At least a part of the sludge 40 to which the polymer flocculant is added is subjected to solid-liquid separation in the concentration unit 16. And the condensed sludge 42 which is the part which the sludge 40 aggregated, and the separation liquid 44 which is mainly a liquid part are discharged | emitted from the concentration part 16 (concentration process).

  The separation liquid 44 is supplied to the phosphorus recovery unit 18. In the phosphorus recovery unit 18, solid phosphorus 46 is recovered from the separated liquid 44 by a crystallization method. Then, the remaining dephosphorization solution 48 is discharged (phosphorus recovery step).

  An inorganic flocculant is added to the aggregated sludge 42 by the inorganic flocculant adding means 20 after being discharged from the concentration unit 16. Then, the coagulated sludge 42 to which the inorganic coagulant is added is supplied to the dewatering unit 22. Then, it is dehydrated by the dehydration unit 22, and the solid content is mainly discharged as the dewatered sludge 50, and the water is mainly discharged as the dehydrated drainage liquid 52 to the mixing unit 24.

The dephosphorization solution 48 and the dehydrated drainage solution 52 are received by the mixing unit 24. When the dephosphorization solution 48 is alkaline and the dehydrated effluent 52 is acidic, mixing is almost neutral (for example, about pH = 6 to 8, preferably about pH = 6.5 to 7.5). Drained liquid 54 is discharged. In this case, it is not necessary to add an acid or alkali for neutralization, which is preferable. However, an acid or an alkali may be added to make it neutral.
The mixed effluent 54 is treated by the activated sludge method in the biological treatment unit 26 (biological treatment step). The treated waste water (biological treatment effluent 55) is subjected to secondary denitrification treatment, aeration treatment, precipitation treatment, etc., if necessary, and then sterilized by being adjusted to alkaline by the sterilization unit 28. The discharged water 56 is discharged.

The deodorizing unit 30, the odor components derived from the sludge 40 by (mainly H ₂ S and methyl mercaptan) recovered, which was deodorized and discharges alkali waste liquid 58 alkaline (deodorizing step).

In the cleaning unit 32, the solid phosphorus 46 is cleaned using the alkaline waste liquid 58 and / or the discharged water 56 (cleaning step).
The solid phosphorus thus obtained is preferable because it is hygienic and dries in a short time.

The apparatus of the present invention further includes a specific gravity separation unit that separates the sludge before or after the addition of the polymer flocculant into a high specific gravity part and a low specific gravity part before the concentration part. It is preferable that the high specific gravity part obtained in the specific gravity separation part is added to the separation liquid, and the low specific gravity part is solid-liquid separated in the concentration part.
The production method of the present invention includes a specific gravity separation step of separating the sludge before or after the addition of the polymer flocculant into a high specific gravity portion and a low specific gravity portion before the concentration step. Further, it is preferable that the high specific gravity portion obtained in the specific gravity separation step is added to the separation liquid, and the low specific gravity portion is solid-liquid separated in the concentration step.
This is because magnesium ammonium phosphate or hydroxyapatite may exist as a solid in the high specific gravity portion, and this is prevented from being included in the solid component by solid-liquid separation in the concentration portion.

  The specific gravity separation part is not particularly limited as long as it can separate the sludge before or after the addition of the polymer flocculant into a high specific gravity part and a low specific gravity part. A hydrocyclone can be used.

It is preferable that the apparatus of the present invention further includes means for supplying the dephosphorization liquid and / or the dehydrated waste liquid to the deodorization unit and cleaning the deodorization unit.
The production method of the present invention preferably further includes a step of washing the deodorization equipment used in the deodorization step using the dephosphorization solution and / or the dehydration waste solution.
It is because generation | occurrence | production of hydrogen sulfide can be suppressed when the said deodorizing part (deodorizing equipment) is wash | cleaned using the said dephosphorization liquid and / or the said dehydration waste liquid.

  Examples of the present invention will be described.

<Example 1>
Sludge treatment was performed using the sludge treatment apparatus 60 shown in FIG. 2, and phosphorus was recovered.
The sludge treatment apparatus 60 will be described.
The sludge treatment apparatus 60 includes a receiving tank 62, a relay tank 64, a polymer flocculant addition apparatus 66, a flocculant tank 68, a concentrator 70, a phosphorus recovery apparatus 72, a circulation tank 74, an inorganic flocculant addition apparatus 75, a dehydrator 76, A separation liquid tank 78, a denitrification tank 80, a nitrification tank 82, a discharge water tank 83, a biological deodorization tower 84, and an alkali cleaning tower 86 are provided. The phosphorus recovery device 72 includes a phosphorus recovery raw water tank 88 and a crystallization reaction tank 90.
Further, the sludge treatment apparatus 60 includes a pipe-like return means 92 for returning the liquid (dephosphorization liquid 106) therein from the circulation tank 74 to the crystallization reaction tank 90. A pH adjuster addition device 94 and a magnesium source addition device 96 that can adjust the pH and magnesium concentration in the crystallization reaction tank 90 as necessary are installed.

The polymer flocculant addition device 66 corresponds to a polymer flocculant addition means that the device of the present invention preferably has.
The concentrator 70 corresponds to a condensing part that the apparatus of the present invention preferably has.
The phosphorus recovery device 72 corresponds to the phosphorus recovery unit in the device of the present invention.
The inorganic flocculant addition device 75 corresponds to an inorganic flocculant addition means that the device of the present invention preferably has.
The dehydrator 76 corresponds to a dehydrating unit that is preferably included in the apparatus of the present invention.
The separation liquid tank 78 corresponds to a mixing section that the apparatus of the present invention preferably has.
The denitrification tank 80 and the nitrification tank 82 correspond to a biological treatment section that the apparatus of the present invention preferably has.
The discharge water tank 83 corresponds to a sterilization unit that is preferably included in the apparatus of the present invention.
The biological deodorization tower 84 and the alkali cleaning tower 86 correspond to a deodorization section that the apparatus of the present invention preferably has.

In such a sludge treatment apparatus 60, first, the sludge 100 is received in the receiving tank 62 and then moved to the relay tank 64. In the relay tank 64, the pH of the sludge 100 received from the receiving tank 62 is adjusted as necessary.
Next, the sludge 100 is moved from the relay tank 64 to the coagulation tank 68, and the polymer coagulant is added from the polymer coagulant adding device 66 in the coagulation tank 68. The agglomeration tank 68 includes a stirrer, which can enhance the action of the polymer flocculant. Thereafter, the sludge 100 to which the polymer flocculant has been added is sent toward the concentrator 70 at a predetermined supply amount. At least a part of the sludge 100 to which the polymer flocculant is added is solid-liquid separated in the concentrator 70. Then, from the concentrator 70, agglomerated sludge 102 which is a part where solid components and the like in the sludge 100 are agglomerated and a separation liquid 104 which is mainly a liquid part are discharged.

  The separation liquid 104 is supplied to the phosphorus recovery raw water tank 88 and further supplied to the crystallization reaction tank 90 at a predetermined supply amount. Further, the concentration of each component in the reaction tank inside the crystallization reaction tank 90 is monitored, and the pH adjuster is appropriately adjusted from the pH adjuster adding device 94 or the magnesium source adding device 96 so that each becomes an appropriate concentration. An appropriate amount of magnesium source is added, or a desired amount of the dephosphorization solution 106 in the circulation tank 74 is added through the pipe-like return means 92. In the crystallization reaction tank 90, solid phosphorus 108 is generated from the separation liquid 104 by the crystallization method, and the remaining dephosphorization liquid 106 is discharged. The solid phosphorus 108 can be recovered from a predetermined location (recovery port) in the crystallization reaction tank 90.

  After the coagulated sludge 102 is discharged from the concentrator 70, an inorganic coagulant is added by an inorganic coagulant adding device 75. The agglomerated sludge 102 to which the inorganic aggregating agent is added is supplied to the dehydrator 76. Then, it is dehydrated by the dehydrator 76, and the solid content is mainly discharged as the dehydrated sludge 110, and the water is mainly discharged as the dehydrated waste liquid 112 to the separation liquid tank 78.

  The dephosphorization liquid 106 passes through the circulation tank 74 and is then received by the separation liquid tank 78. Then, the dephosphorization liquid 106 and the dehydrated waste liquid 112 are mixed in the separation liquid tank 78, and the mixed waste liquid 114 is discharged from the separation liquid tank 78. When the dephosphorization liquid 106 is an alkaline liquid and the dehydrated effluent 112 is an acidic liquid, the mixed effluent 114 can be made almost neutral. The treatment can also be performed in a denitrification tank 80 and a nitrification tank 82).

  The discharged mixed effluent 114 is sent to a denitrification tank 80, further processed in a nitrification tank 82, and further subjected to secondary denitrification treatment, aeration treatment, precipitation treatment, etc. as necessary, and then a discharge water tank. 83 is stored. Then, after sodium hypochlorite is added in the discharge water tank 83, it is discharged as discharge water 116. Here, sodium hypochlorite is added so that the concentration of sodium hypochlorite contained in the discharge water 116 is about 0.1 to 0.2 mg / L.

In the biological deodorization tower 84, high-concentration odor components (mainly H ₂ S) derived from the sludge 100 generated from a plurality of locations in the sludge treatment apparatus 60 are collected and biologically treated. The generated exhaust gas 118 is sent to the alkali cleaning tower 86.
In the alkali cleaning tower 86, medium-concentration odor components (such as methyl mercaptan) generated from a plurality of places in the sludge treatment apparatus 60 and derived from the sludge 100 are collected. In addition, the exhaust gas 118 generated in the biological deodorization tower 84 is also recovered. In the alkali cleaning tower 86, the medium concentration odor component and the exhaust gas 118 are cleaned using sodium hypochlorite and sodium hydroxide. The alkaline waste liquid 120 discharged from the alkali cleaning tower 86 contains sodium hypochlorite and sodium hydroxide.

Each part in such a sludge treatment apparatus 60 is specifically as follows.
- receiving tank 62: reinforced concrete water tank and relay tank 64: reinforced concrete water tank, polymer coagulant addition device 66: stirrer with 2.0 m ³ tank and metering pump, flocculation tank 68: hydraulic residence time 3-5 minutes, stirring Thoroughly mixable in a tank with a machine.
Concentrator 70: slit type concentrator (aperture 0.5 to 1.0 mm)
・ Phosphorus recovery device 72
-Phosphorus recovery raw water tank 88: tank with stirrer-Crystallization reaction tank 90: Two-column crystallization reaction tank (as described in Japanese Patent No. 4053273), made by Mizuing Co., Ltd.-Circulation tank 74: Tank-Inorganic flocculation Agent addition device 75: 3.0 m ³ tank and metering pump / dehydrator 76: screw press machine: shaft sliding screw press, manufactured by Watering Co., Ltd., separation liquid tank 78: reinforced concrete water tank / denitrogenation tank 80: Reinforced concrete water tank / nitrification tank 82: Reinforced concrete water tank / discharge water tank 83: Reinforced concrete water tank / biological deodorization tower 84: Filled scrubber tower / alkali cleaning tower 86: Filled scrubber tower / return means 92: Spiral pump / pH adjuster Adder 94: 20L tank and pump Magnesium source adder 96: 50L tank and pump

In the sludge treatment apparatus 60, the sludge 100 was treated under the following conditions.
Sludge 100: Mixture of human waste and septic tank sludge Treatment amount of sludge: 10.8 m ³ / day Inflow PO ₄ -P load: about 1.0 kg-PO ₄ -P / day Polymer coagulant: amphoteric polymer ( CS-302), manufactured by Mizuing Co., Ltd., pH adjuster: sodium hydroxide (added so that the pH meter installed in the circulation tank is around 8.7 to 9.5)
Magnesium source: Magnesium chloride (10% by mass—dissolved to use MgCl)
Inorganic flocculant: polyferric chloride, concentration 11% by mass-Fe (specific gravity 1.45)

  When the sludge 100 was processed using such a sludge processing apparatus 60, it was possible to recover phosphorus at 1.0 kg-MAP / day as magnesium ammonium phosphate (MAP). Moreover, the dehydrated sludge could be made into the low water content of 63-70 mass%.

  The solid phosphorus 108 collected as described above was washed by the following method.

The alkaline waste liquid 120 discharged from the alkali cleaning tower 86 was sampled. Further, the solid phosphorus 108 was extracted from the crystallization reaction tank 90 and sampled.
When the pH and components of the alkaline waste liquid 120 were examined, the pH was 10.2, the sodium hypochlorite concentration: 440 mg / L, and the M-alkalinity: 3140 mg / L (as NaOH: about 0.25% by mass). .

  Next, the extracted solid phosphorus 108 was charged into a 200 ml beaker by about 1/5 by volume, and the sampled alkaline waste liquid 120 was further charged to obtain a sample having a total volume of 200 ml. Further, two 200 ml beakers were prepared, and each of them was charged with solid phosphorus 108 and alkaline waste liquid 120 in the same manner to obtain a total of three samples. And about the obtained three samples, it stirred using the spatula. The stirring time was changed to 30 seconds, 60 seconds, and 180 seconds for each sample.

After stirring and washing for each sample, water was roughly separated using a filter paper and a funnel. The filter paper was spread in the laboratory and allowed to dry naturally for 24 hours. Thereafter, the number of surface coliforms and water content (% by mass) of phosphorus obtained from each sample were measured.
The results are shown in Table 1.

  The number of surface coliforms and the water content were measured according to the sewer test method.

<Example 2>
Sludge treatment was performed using the same sludge treatment apparatus 60 as in Example 1, and phosphorus was recovered.
In the first embodiment, the alkaline waste liquid 120 discharged from the alkaline cleaning tower 86 is sampled and the solid phosphorus 108 is washed using this, but in the second embodiment, the effluent water 116 is sampled and this is used. Used to wash the solid phosphorus 108. Then, all other operations were carried out in the same manner as in Example 1, and the number of surface coliforms and the water content (mass%) of phosphorus obtained from each sample were measured.
The results are shown in Table 2.

In addition, when pH, a component, etc. of the discharge water 116 were measured, they were as follows.
pH: 5.8 to 8.6
BOD: 10 mg / L or less COD: 30 mg / L or less SS: 10 mg / L or less TN: 20 mg / L or less TP: 1 mg / L or less E. coli group number: 1,000 / cm ³ or less

<Comparative Example 1>
Sludge treatment was performed using the same sludge treatment apparatus 60 as in Example 1, and phosphorus was recovered.
And about the obtained phosphorus, after separating the water roughly using a filter paper and a funnel, the filter paper was spread in the laboratory and allowed to dry naturally for 24 hours. Thereafter, the number of surface coliforms and water content of the obtained phosphorus were measured in the same manner as in Example 1.
As a result, the number of surface coliforms was 32895 / g. The water content was 22.5% by mass.

<Comparative example 2>
Sludge treatment was performed using the same sludge treatment apparatus 60 as in Example 1, and phosphorus was recovered.
And about the obtained phosphorus, after separating water roughly using a filter paper and a funnel, the filter paper was spread in the laboratory and air-dried. And the period until a moisture content became about 2 mass% was measured. As a result, it was found that natural drying for about one month was necessary for the moisture content of phosphorus to be about 2% by mass.

  Comparing the results of Example 1, Example 2, Comparative Example 1 and Comparative Example 2, in the case of Example 1 and Example 2, the number of surface coliforms decreased dramatically in a short time. It can be seen that the time until the moisture content reaches a low level (about 2% by mass) is much shorter.

DESCRIPTION OF SYMBOLS 12 Reception part 14 Polymer flocculant addition means 16 Concentration part 18 Phosphorus collection | recovery part 20 Inorganic flocculant addition means 22 Dehydration part 24 Mixing part 26 Biological treatment part 28 Sterilization part 30 Deodorizing part 32 Washing part 40 Sludge 42 Aggregated sludge 44 Separation liquid 46 Solid phosphorus 48 Dephosphorization liquid 50 Dehydrated sludge 52 Dehydrated waste liquid 54 Mixed waste liquid 55 Biological treatment waste liquid 56 Effluent water 58 Alkaline waste liquid 60 Sludge treatment apparatus 62 Receiving tank 64 Relay tank 66 Polymer flocculant addition apparatus 68 Coagulation tank 70 Concentrator 72 Phosphorus recovery device 74 Circulation tank 75 Inorganic flocculant addition device 76 Dehydrator 78 Separation liquid tank 80 Denitrification tank 82 Nitrification tank 83 Discharge water tank 84 Biodeodorization tower 86 Alkaline washing tower 88 Phosphorus recovery raw water tank 90 Crystallization reaction tank 92 Return means 94 pH adjuster addition device 96 Magnesium source addition device 100 Sludge 102 Agglomerated soil 104 separated liquid 106 dephosphorization liquid 108 solid phosphorus 110 dewatered sludge 112 dewatering drainage 114 mixed effluent 116 effluent 118 exhaust gas 120 alkaline waste

Claims (6)

A sludge treatment device that treats sludge, collects phosphorus, and discharges discharged water,
Applying a crystallization method, a phosphorus recovery unit that recovers solid phosphorus, which is solid phosphorus,
A washing section for washing the solid phosphorus with an alkaline solution;
A sludge treatment apparatus. Furthermore, the odor component generated from the sludge is collected, deodorized, and has a deodorization unit that discharges alkaline waste liquid.
The sludge treatment apparatus according to claim 1, wherein the alkaline waste liquid is used as the alkaline solution in the cleaning unit. Furthermore, it has a sterilization section that discharges the discharged water adjusted to be alkaline,
The sludge treatment apparatus according to claim 1 or 2, wherein the discharged water is used as the alkaline solution in the cleaning unit. A method for producing phosphorus, treating sludge to recover phosphorus and discharging discharged water,
A phosphorus recovery step of recovering solid phosphorus, which is solid phosphorus, by applying a crystallization method;
A washing step of washing the solid phosphorus with an alkaline solution;
The manufacturing method of phosphorus which has this. Furthermore, the odor component generated from the sludge is collected, deodorized, and has a deodorization step of discharging the alkaline waste liquid,
The method for producing phosphorus according to claim 4, wherein in the washing step, the alkaline waste liquid is used as the alkaline solution. Furthermore, it has a sterilization process to discharge the discharged water adjusted to alkaline,
The method for producing phosphorus according to claim 4 or 5, wherein, in the washing step, the discharged water is used as the alkaline solution.

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